1. Field of the Invention
The present invention relates to a technique of a microscope for observing a specimen mounted on a stage, and more particularly, to a microscope appropriate for micro insemination and a controlling method of the microscope.
2. Description of the Related Art
Recently, as one use of a microscope, micro insemination is known in the field of advanced reproductive medicine. The micro insemination is a process of fertilizing an egg with sperm under a microscope. In general, the micro insemination is performed by an intracytoplasmic sperm injection (hereinafter, referred to as “ICSI”) method of piercing an egg fixed by a holding pipette with a sperm-containing micropipette to inject the sperm into the egg. In the ICSI, since a specimen is manipulated on a stage, an inverted microscope with a large working space above the stage is generally used.
In addition, in the field of the micro insemination, a relief contrast microscopy (hereinafter, referred to as an “RC microscopy”) capable of stereoscopically observing an egg in order to improve an egg fertilization rate is known (refer to, for example, Japanese Laid-open Patent Publication No. 51-29149).
In addition, recently, in the field of the micro insemination, a micro insemination method of using a microscope while appropriately switching a plurality of observation methods in order to improve the fertilization rate has received attention. For example, a method of using a microscope while switching among an RC microscopy, a differential interference contrast microscopy (hereinafter, referred to as a “DIC microscopy”), and a polarized light microscopy (hereinafter, referred to as a “PO microscopy”) depending on observation purpose is prevalent.
In the DIC microscopy, it is possible to observe an object at high magnification in comparison to the RC microscopy. Therefore, the DIC microscopy is suitable for observation of a sperm which is smaller than an egg. Accordingly, the DIC microscopy is used to select a good-quality sperm.
In addition, the PO microscopy is suitable for observation of a spindle of an egg having birefringence. Therefore, the PO microscopy is used to identify the position of the spindle while preventing the spindle from being mistakenly damaged at the time of injecting a sperm into the egg.